1. Field of the Invention
This invention generally relates to a luminous display board, and more particularly to a flat type luminous member that illuminates characters or pictures drawn on a greeting card, a card attached to a bouquet, a display or the like from the back side thereof.
2. Description of the Relevant Art
Luminous members which emit light through chemical luminescence have heretofore been used as illumination sources such as, a flashlight, an emergency light, a float light for fishing or the like. This type of luminous member has a light-transmitting cylindrical flexible plastic receptacle container filled with a solution and a glass ampule. A reactive substance (e.g., an oxalic acid derivative and a fluorescent substance) are filled in the container, and a solution (e.g., hydrogen peroxide, a catalyst or the like) are filled in the glass ampule, sealed therein, and inserted into the flexible plastic container. These substances emit a light by excitation when reacted with each other.
When the luminous member is used to emit light, the above-described flexible container is folded to break the glass ampule inside the container and then shaken in order to mix two kinds of solutions with each other. As a result, the above-mentioned reactive substance and hydrogen peroxide react with each other in order to excite the fluorescent substances so that light is emitted therefrom.
In the western world, including Europe and the United States, it is customary to present greetings on occasions, such as Christmas and birthdays. These types of greetings have recently become widely accepted in Japan.
Furthermore, instead of a "New Year" letter, some Japanese now tend to send a greeting card.
In order to give a good impression to people who receive greeting cards, there are various kinds of cards, for example, a card with various designs, a card which becomes three-dimensional when it is opened or a card which makes a sound when it is opened. Therefore, by using the above-described chemical luminescence, characters or pictures drawn on a greeting card, for Christmas or birthday or a card attached to a bouquet, a display or the like, can be illuminated from the back side thereof in order to stand out and attract attention.
It is also considered to use the above-mentioned chemical luminescence for a display board at night, for example, for use as a guidance board for guests in a funeral or the like.
However, the above-described prior art luminous member has a drawback in that the card or display board is required to be thick because the luminous member itself is cylindrical. Thus, the above-described conventional luminous member is not suitable, especially for a card having an image and for illuminating characters or pictures drawn on the surface from the back side thereof.
Therefore, the luminous member is required to be flat. However, it is not necessary to illuminate all of the surfaces of the card or board, but it is necessary to partially cover the surface of the card or board by a shield in order to illuminate certain parts of the surface. The cost of such a luminous member would be high because the chemical luminescent solution for the portion which is shielded is expensive and is made useless.
If the above-described luminous member is enclosed within a cover which has at least some light-transmitting portion, and is composed of a card or display board, even if it is about the same size as the luminous member in order to avoid a flexible luminous member, the cost will also be high because the chemical luminescence solution for the non-light-transmitting portion is useless.
Therefore, considering the above-described situations, it is an object of the present invention to provide a flat luminous display board which makes use of the chemical luminescence solution for the luminescent portion.
It is noted that a flat shaped luminous display board has another problem; namely, the reaction of an oxalic acid derivative with hydrogen peroxide to excite a fluorescent substance to emit light causes the occurrence of carbon dioxide gas in the container. Therefore, if the flexible plastic container is flat shaped, the front side and the back side of the container becomes swollen due to the enlargement of the bulk of the container in opposite directions from the pressure of the carbon dioxide gas. In other words, the flat shape of the container becomes deformed. When the container is standing up, it will cause the level of chemical luminescent solution to descend to a lower level so that an upper portion of the standing flat shaped display will not emit the light.
If the flexible plastic container is cylindrical, the increased pressure due to chemical reaction will equally push the inner portion of the cylinder, and will cause the cylindrical container to expand slightly. If the flexible plastic container is flat shaped, both sides of the container will expand, then stress will concentrate towards the edge portion of the container which will break the container causing leakage of the solution; especially, in the case where the flat shaped container has a special inlet where glass ampules are used, and a cap thermally sealed to the inlet, the stress due to the increase in the gas pressure will concentrate on the thermally sealed cap portion to destroy the seal. If the thermal sealing is made strong enough to endure the stress, then it will be expensive.
Therefore, considering the above-described problems, it is an object of the present invention to provide a flat luminous display board which can prevent deformation or destruction of the flat shaped container due to increase in the gas pressure due to chemical reaction.